The best ruler will be dependent on your cutting set up. For years, I did all my cutting on what is now a “vintage” 18x 24 mat made by Dritz on the floor, but now that puts too much strain on my aging body. So I now use a 13x 13 mat on my ironing board. I typically use my 6x 12 as my primary ruler and a 15 x 15 for everything too big for that. I only use my 6x 24 for trimming quilt edges on that trusty 18x 24 mat. I have a couple of small rulers that I use for measuring more than cutting. My only speciality ruler is the Bonnie Hunter Essential Triangle tool. When I recently needed a tool to trim flying geese, I added tape marks on a small ruler.